1. Field of the Invention
The present invention relates to a broadband wireless communication system. More particularly, the present invention relates to an apparatus and method for transmitting a load indicator in a broadband wireless communication system.
2. Description of the Related Art
Load-aware Base Station (BS) selection is a scheme in which a Mobile Station (MS) determines a load state of BSs and selects a serving BS based on the load state. The load-aware BS selection can provide efficient system resource utilization and allow improved quality of communication for users. To support this scheme, each BS broadcasts a load indicator to inform of its own load state. Commonly, a resource utilization ratio is used as the load indicator.
In the case of traffic with a fixed rate such as voice communication, it is reasonable to use the resource utilization ratio as the load indicator. However, in the case of traffic such as Transmission Control Protocol (TCP) for adaptively increasing a data rate according to bandwidth margin through an end-to-end flow control, it is unsuitable to use the resource utilization ratio the load indicator. For example, if there is single traffic with a dynamic rate, such as TCP, in a cell, a radio resource utilization ratio can be equal to 100%. However, based on the rate constraint, the cell can be serviced by new traffic and additionally provided with traffic with another dynamic rate. That is, in a case where it is intended to add traffic with a rate constraint such as real-time traffic, the traffic with the rate constraint can be added by preempting a resource of the traffic with the dynamic rate through prioritized bandwidth assignment.
As described above, when a resource utilization ratio is equal to 100%, new traffic can be added due to traffic with a dynamic rate. However, despite that the addition of the new traffic is possible, a load indicator based on a resource utilization ratio fails to indicate a concrete characteristic on a load state. Therefore, the addition of new traffic is interrupted.
Therefore, a need exists for an apparatus and method for transmitting a load indicator of a serving BS in a broadband wireless communication system.